FADU F-STOP ENLARGER TIMER

The project files for the FADU F-stop Enlarger Timer have now been moved to GitHub as that is a more appropriate place to maintain the project - but read on for an overview and release...

Hi Ariel.

Phew... I got the OTA to work by following your experience (and after some issues caused by my weird and rubbish cable router)!

I will write this all up in the manual and upload a new version to the google Play Store with the additional features I mentioned earlier.

I have experimented with the unprogrammed DIY API mode some more and obtained actual timings of the sonoff's relay switching times and unfortunately the delays though the router occasionally cause a >1/3rd stop error - about once in every 20 strips. It may improve if using a dedicated router but I do not have a spare one - at some point I will get an old one and experiment again.

BTW, I don't know if you have already discovered this yourself, but when having an issue not being able to pair to the Sonoff a second time (such as after you give it the wrong SSID), I have found that using eWeLink to pair to the Sonoff and then Deleting it from eWeLink forces a factory reset which allows you to go through the linking to DIY mode again successfully.

Hi Bob,
In my case it wasn't necessary, because I could reprogram my sonoff as I explained. But I discovered that helping other people to configure their sonoff. Yes, after I published the article, I found a lot of interested people in the spahish speakers analog photography community. And some of them are using the new unpublished version...

Been a busy couple of days. I have added a few upgrades to the work in progress version at https://github.com/filmanddarkroom/FADU_Timer/tree/wip

The main update is that using the Sonoff Basic R3 or Mini R3 in DIY mode now has the option to use the "Inching" API call to pulse the lamp on and then off without having to send an OFF command which avoids random router delays (but adds small inaccuracies which seem well worth the trade-off).

If I can stop myself fiddling any more with it, I will update the manual and publish the update to the google Play Store in the next few days.


Work In Progress Version 1.4.2 [believed stable]:


(1) Added [PULSE R3] mode. Similar to (2) below but uses the "inching" mode of the R3 DIY mode API (http://developers.sonoff.tech/basicr...-http-api.html) to send fixed duration lamp-on commands to the Basic R3 or Mini R3 in DIY mode. For example, we send a command that says "switch on for 17.5 seconds and then switch yourself off". The app does not need to send the OFF signal and hence avoids random timing delays through the router. Set [PULSE R3] to use.

Of course, Sonoff have once again messed things up - in this case by only allowing multiples of half a second to be set! This does not help with accuracy but is not as bad as it first seems for typical lamp ON times of several seconds and it does at least mean that the timing is consistent, which you could argue is more important.

The worst-case error when rounding to the nearest 0.5s is 0.2s. The percentage error depends on your base time. For example, 10.7 seconds will round down to 10.5s which is an error of just 1/37th of a stop which is not detectable by the human eye. Longer times will be more accurate but shorter times will be worse: 5.3s for example would round to 5.5s which is an error of 1/19th of a stop - which I think is still very acceptable. I prefer the repeatability of the timings in this mode over the random router dependent delays in (2) below.


(2) Added the ability to select a Sonoff R3 device in DIY mode. Tested with a Mini R3 running version 3.5 of the Sonoff firmware. Option "BASIC R3" added to the Settings tab's "Lamp Controller" section. To use: Place your R3 device into DIY mode per Sonoff's instructions. Once working in DIY mode, set the IP Address of the R3 device in the IP ADDRESS section in the SETTINGS tab (just the IP address, do not add the port etc - this is added in the app's code): e.g. 192.168.0.22 It may be a freak of my network router but I had to use Fing on my phone to find the device's IP address - it did not appear on my router's list of connected devices - very odd.

The downside of this mode is that all the on and off signals go via your WiFi router which adds random delays of typically 5 - 100ms on my network - and occasionally more. 100ms is just under 1/8th of a stop for a 1 second time exposure so you will need to consider if this is still sufficient accuracy for your purposes. In practice, I could only empirically detect a delay once in every ten or twenty switches. If you have a spare WiFi router then creating a separate network and dedicating this to the timer with no other devices or Internet connection would make these delays both smaller and much less random in duration allowing you to use the timer's Lamp Adjust setting to compensate. I have not tried this but it should work well (in theory!). Alternately, consider using the [PULSE R3] mode described above in (1).


(3) Added the ability to use the camera's flash LED. I'm not entirely sure what use this is except for demo or testing purposes. Possibly could be used for flashing paper if you add a diffuser over the LED and use the Delay setting to give you time to raise it to the right height after setting the time. Light activated relay boards do exist but keeping the bright light out of the rest of the darkroom may prove difficult.


(4) Added individual volume controls for the various beeps and buzzes (scroll down the SETTINGS tab if you don't see them). A bit tricky to use due to being small (I could find no way to enlarge them in App Inventor). The settings are reloaded the next time the app is launched.


(5) You no longer need to use the [SET] button on the STRIPS tab: the strips times automatically update when changing the base time or opening the STRIPS tab. The [SET] button is retained although it is now mostly redundant.


The manual still requires updating from release version 1.4.